Grounded surface distribution apparatus

ABSTRACT

A grounded surface distribution apparatus and system is provided including elastomer encapsulated cable terminals, joints, taps, load-break switches, current limiting fuses and surge protectors, each enclosed completely within a metal sheath combined in various arrangements to perform operational functions required in loop and radial underground distribution systems. The cable terminals include a soft dielectric filler making a void-free interfacial engagement with the surface of a hard dielectric filler of a mating component. To provide for breaking a coupling under load, an arc-quenching follower is retractable into an axial cavity in the coupling components of the system and projectable therethrough upon breaking of the circuit and disconnecting of the components to provide an improved arcquenching function. Thus, there is provided an underground system having security, operational safety and convenience.

United States Patent 1 1 Yonkers [76] Inventor: Edward H. Yonkers, 905

Westerfield Dr., Wilmette, 111. 60091 [22] Filed: Apr. 12, 1971 [21]Appl. No.: 133,357

Related U.S. Application Data [60] Division of Ser. No. 4,396, Jan. 20,1970, which is a continuation of Ser. No. 660,748, Aug. 15, 1967,abandoned.

[52] us. Cl. 337/201, 174/73 [51] Int. Cl. H0111 85/02, 1-102g 3/00,l-lOlr 13/46 [58] Field of Search 337/199, 201, 202, 222, 337/224;174/73 [56] References Cited UNITED STATES PATENTS 1,730,716 10/1929Austin .Q 337/222 2,660,644 11/1953 Murray et al. 337/224 3,309,4774/1967 GROUNDED SURFACE DISTRIBUTION APPARATUS Bronikowski 337/199 X1451 Feb. 25, 1975 Primary ExaminerJ. D. Miller Assistant ExaminerFredE. Bell Attorney, Agent, or FirmMason, Kolehmainen, Rathburn & Wyss [57]ABSTRACT A grounded surface distribution apparatus and system isprovided including elastomer encapsulated cable terminals, joints, taps,load-break switches, current limiting fuses and surge protectors, eachenclosed completely within a metal sheath combined in variousarrangements to perform operational functions required in loop andradial underground distribution systems. The cable terminals include asoft dielectric filler making a void-free interfacial engagement withthe surface of a hard dielectric filler of a mating component. Toprovide for breaking a coupling under I load, an arc-quenching followeris retractable into an 25 Claims, 27 Drawing Figures ,Pmmm wz 3,868,616SHEET DlUF 13 FIG, FIG. 2

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INVENTCR: EDWARD H. YONKERS ATT'YS PATENTED 3.868316 SHEET 13UF 13INVENTOR" EDWARD H. YONKERS GROUNDED SURFACE DISTRIBUTION APPARATUS Thisapplication is a division of Ser. No. 4,396, filed Jan. 20, 1970, whichis a continuation of Ser. No. 660,748, filed Aug. 15, 1967, nowabandoned.

The present invention relates to a new and improved grounded-surfacedistribution apparatus and system for underground installation such asrequired in loop and radial underground distribution systems. Moreparticularly, there is provided unique cable-terminal loadbreak switchelements which make possible hot-stick disconnecting, switching,sectionalizing and the like without moving the cable or the cableterminals and providing visible separation between grounded-surfacecircuit elements. p

The present strong trend toward underground distribution of electricitybrings with it the need for new kinds of associatedapparatus to providethe necessary system functions including switches,-fuses, surgearrestors, cable terminals, taps and joints. The newaspect of suchapparatus is that it must be able to carry on its functions undergroundin contact with and at times under water. This means that every part ofthe circuit which is maintained at system potential must be sur-'rounded by a continuous sheath of impervious, voidfree insulation withina continuous conductive grounded housing. v

Commercial apparatus attempting to fulfill these difficult requirementsis still in the early stages of development. Prior known apparatus hasnot been entirely successful. In fact, the trend toward such undergrounddistribution systems is so new that standard nomenclature has not beenestablished by the electrical industry. The term submersible issometimes applied to these devices for Want of a more appropriate term.Groundedsurface distribution apparatus is a more appropriate and moretruly descriptive term for this class of equipment since a conductivegrounded-outside surface is a function requirement for operational andsafety reasons.

The essential and main ingredient in underground distribution ofelectricity is obviously cable which must carry distribution current andvoltage underground with trouble-free long life performance. Recentdevelopments in synthetic dielectric materials have made possible theproduction of solid polymer insulated cable with high performance andlow cost. However, the advantages of the new cable cannot be realizedfully without effective, safe and convenient means for connecting thecable to various devices required in underground distribution systems.By employing voltage A further object of the present invention is theprovision of a new and improved distribution system suitable forunderground and submersible installation.

A further object of the present invention is the provision of a new andimproved cable terminal for a groundedsurface distribution system.

A further object of the present invention is the provision of a new andimproved coupler for a distribution cable.

A further object of the present invention is the provision of a new andimproved load-break coupling suitable for grounded-surface distributionsystem application.

Yet a further object of the present invention is the provision of a newand improved arrangement of taps and connecting units for an undergrounddistribution grading and interfacial sealing techniques, it has beenpossible to provide grounded-surface submersible devices to performfunctions of cable joining and terminating, load-break switching,sectionalizing, and fusing.

The term grounded-surface may be taken literally in that apparatus inthis category does in fact have a grounded external surface preferablyof metalvthick enough to provide mechanical support and to carry faultcurrent if it occurs. Conductive plastic coatings will perform part ofthe function of grounding the surface but they may not provide safetyunder fault conditions.

Thus, it is an object of the present invention to provide a new andimproved grounded-surface distribution system.

system.

A further object of the present invention is a new and improved surgearrestor for a grounded-surface distribution system.

Another object of the present invention is the provision of a new andimproved fuse structure for a grounded-surface distribution system. Thedifficult design problem in grounded-surface distribution apparatus isto put the entire high potential circuit inside the grounded housingsand still provide means for carrying out switching and sealing-offfunctions. In accordance with thepresent invention there is provided asystem which employs a combination of soft and hard dielectrics castinto place around the high voltage elements with compression springs atappropriate locations to maintain all critical interfaces void-free andunder pressure over all ambient variations expected in operation.

In accordance with one aspect of the invention each circuit ismaintained separately in its own grounded sheath with'interfittingcomponents available to set up various functions such as load-breakdisconnect. In this case the two cable terminals are supported by arigid clamp mounted on a ground rod. The load-break features are presentin both cable terminals independent or latched over the elements of theopen switch, if desired. Thus, the switch whether open with separatecaps or closed with the U coupling, is completely safe and withouthazard to operating personnel working in close proximity to it. p

In accordance with another aspect of the present invention, the morecomplicated arrangements carry the same features of system, security,operating convenienceand safety. For example, a three terminal tapswitch arrangement according to the present invention is very effectivein loop systems where sectionalizing is needed.

In accordance with the present invention a groundedsurfacecurrent-limiting fuse provides system security when used in the tapcircuits.

An improved surge arrestor provides convenient means for surgeprotection of the open position in loop circuits. Such a surge arrestoris also equipped for installation or removal with a hot stick.

The basic element of the present grounded-surface distribution apparatusis the cable terminal. 'It performs several important functions; (I)connection to the cable conductor, (2) grading of the field andprovision of a permanent seal over thecable insulation, (3) provision ofa disconnect and load-break element, (4) provision of a standard conicalsealing surface to mate with various elements such as couplers, fuses,insulating and grounding covers, and to provide intertitting of variouselements having high versatility in meeting circuit requirements bymeans of a rigid cylindrical housing of stainless steel-with locatingmeans in precise bracket structures. All of the interfitting elementsemploy the same standardized conical sealing surface and latch springgeometry. The grounded cover of the cable terminal is latched into placeproviding the standardized conical seal which is waterproof due to thevoid-free interface held-under permanent pressure by the latch springs.a

.In accordance with one aspect of the invention wherein a U? coupler islatched in place between two cable terminals, the U coupler may readilybe removed with. a hotstick to provide load-break disconnectingfThe Ucoupler and associated load-break terminals easily meet the usualrequirement encountered with single phase distribution systems. The'con-Centric neutral wires of the cable are connected directly to the cableterminal housing and serve to hold the cable in place by means ofsplit'bolt connectors, then continue on to be connected together and toground. This firm connection is particularly important where systemfault currents are high.

The present devices are particularly well adapted for sub-surfaceswitching points or controlcenters. In such control center arrangementsthe loop can be separated and part of it temporarily grounded with agrounding cover and also it may be sealed off in the open position withan insulating cover or a surge arrestor. Versatile components thusprovide means for safely controlling, protecting and servicingunderground single phase loop orradial systems. Maximum safety isafforded to operating personnel by virtueof the continuous groundedsheath which coversall'en'ergizecl elements with rugged stainless steelwhich can carry the high fault currents which sometimes occur indistribution systems.

Another safety feature which is inherent in the grounded-surface systemis that open circuit positions always provide visible separation withsolidly grounded elements between the separate circuit terminals. Thus,when'all circuit terminals are sealed and latched with couplers, fuses,arrestors, covers or the like as required,

the sub-surface control centers provide the maximum in circuitreliability, the minimum in customer outages, and maximum in safety andconvenience for servicing. For a better understanding of the presentinvention, reference may be had to the accompanying drawings wherein:

FIG. 1 isan isometric view of a cable terminal with a grounding cap inplace according to the present invention;

FIG. 2 is a cross sectional view of the cable terminal of FIG. 1, andillustrating the electrical coupling components within the cableterminal;

FIG. 3 is a cross sectional view of the cable terminal of FIG. 1, takenalong line 3-3 of FIG. 2, and illustrating the plug-in connectorcomponents within the cable terminal;

FIG. 4 is a cross sectional view of the connector coupling components ofFIG. 3, illustrated to a larger scale;

FIG. 5 is an exploded view of the coupling components of FIGS. 3 and 4;

FIG. 6 is an isometric drawing illustrating a grounded-surfaceload-break switch employing two standard load-break cable terminals anda standard U" coupler.

FIG. 7 is a cross sectional view of a .U coupling unit taken along line7-7 of FIG. 6;

FIG. 8 is a cross sectional view of the U" coupling unit of FIG. 7,taken along line 8-8 of FIG. 7, assuming that FIG. 7 illustrates theentire structure;

FIG. 9 is a top view of a single taparrangement employing threeloadbreak. cable terminals, and a tap manifold or bus in accordance withthe present inven tion;

FIG. 10 is an elevational view of the structure of FIG. 9 and furtherillustrating U couplers in phantom;

FIG. 11 is an elevationalview of a three-point manifold or bus of thetype illustrated in FIGS. 9 and l0, illustrated in broken away section;

FIG. 12 is an elevational view of a surge, protector for use with acable terminal according to the present in-- vention and illustratedpartially in broken away section;

FIG..1-3 is a top view of the surge protector of FIG. 12;

FIG. 14 is a cross sectional view of a current limiting fuse for usewith terminals according to the present invention;

FIG. 15 is an alternate structure of a fuse connector for use withterminal taps according to the present invention and illustrating aremovable fuse arrangement;

FIG. 16 is an end view of the fuse structure of FIG.

FIGS. 17 and 18 illustrate an alternate control center arrangementincluding a connecting unit having multilevel terminals to providedesired economy of space and apparatus;

FIGS. 19 and 20 illustrate the isolating or grounding of one of thelines in the control center of FIG. 17;

FIG. 21 illustrates in crosssection a primary cable terminal for thegrounded surface submersible system according to the present invention;

FIG. 22 illustrates in broken away section a cable joint according tothe present invention;

FIG. 23 is an end or bottom view of thecable joint of FIG. 22 takenalong line 23-23 of FIG. 22;

FIG. 24 is a cross sectional view of the cable joint of FIG. 22, takenalong line 24-24 of FIG. 22;

FIGS. 25 and 26 illustrate a switching point assembly employing animproved T terminal; and

FIG."27 illustrates a sub-surface switching point assembly. I

Referring now to the drawings and particularly to the embodiment ofFIGS. 1, 2 and 3, there is shown the details of a cable terminal 30 witha grounding cover 32 latched in sealed position. The cable terminal 30includes a conducting housing 34 of suitable material such as stainlesssteel, and cylindrical in cross section.

A cover 35 also of conducting material such as stainless steel engagestwo side pins 36 in the housing 34 in a spiral bayonnet action tocompress an inner'thrust spring 37 to be compressed in the latchedposition as shown so as to exert an axial thrust on a soft elastomerdielectric filler 38 confined at its lower end by a piston-like cupretainer 39. i

The soft dielectric filler 38 is cast within the housing 34 to interfitwith a hard dielectric filler 40 which is firmly cast and locked intothe housing 34 but which projects from the end of the housing to providea standardized conical sealing surface 41 having a connector entrance42. Although the hard dielectric filler 40 is illustrated as formed oftwo parts 40a and 40b, it may be made of one piece if desired.

As used herein, the soft dielectric filler may be of any void-freedielectric soft enough to conform to the adjacent surfaces in void-freeinterfacial engagement under the loading of the selected thrust spring.It has been found that a soft poly-urethane or other limited crosslinked polymer, preferably castable, with a Shore A hardnessof to 40,worked satisfactorily. As used herein, the hard dielectric filler may beof any void-free dielectric hard enough to provide mechanical strengthto position the components. Castable synthetic polymers such as epoxyresins having a Shore A of 100 or higher were found satisfactory.

The soft dielectric filler 38 is designed to receive a power cable 45 ofthe type having a basic insulation 46 and a sheath 47 as customizeddimensions. In addition to the sheath 47, the cable 45 may contain aplurality of strands of grounding wire 48. The end thrust spring 37permits a reasonable range in diameter variation and still maintains apermanentvoid-free interfacial seal between the insulation 46 and thesoft elastomer 38 even under submerged conditions.

The cable terminal includes a connector 50 for terminating the end ofthe cable and defining a cable connector 500 at one end. The cableconnector a has an elongated body of conducting material, such as copperand the like, and defines a receptacle 51. A conducting pin or plug 52is adapted for insertion into an elongated axially aligned pin cavity 53of the receptacle S1 to establish a low resistance connection capable ofcarrying rated current as well as momentary high currents. The pin 52 isconnected to the short exposed end 45a, FIG. 2, of the cable 45, and thepin 52 is formed with an elongated axially aligned socket 54 extendinginwardly from the lower end of the connector. After the centralconductor 45a is inserted into the socket 54, a compression tool or thelike is'used to compress the walls of the socket inwardly into tightengagement with conductor 45a and thus firmly secure and electricallyconnect the pin 52 to the upper end of the cable 45. The pin 52 includesa cylindrical pin portion 55 of reduced diameter adapted to be insertedinto the pin cavity 53 of the receptacle 51 to establish electricalconnection therewith.

The receptacle 51 around the pin cavity 53 thereof ity of movablefingers 62, each including one of the ridges 59 and a pair of segmentson its outer surface and a curved segmented, cylindrical interfaceforming a wall portion of the pin cavity 53. The free ends of thefingers 62 are movable inwardly and outwardly with respect to thelongitudinal central axis of the receptacle 51 and form the lower endportion thereof surrounding the pin cavity 53.

In order to establish a relatively high contact pressure between thefingers 62 and the pin 52 and thereby further reduce the resistance ofthe connection and increase the current carrying capacity thereof, thefingers 62 are biased inwardly by a circular tension ring 63 which isslipped over the body of the receptacle 51 and bears against theflattened surfaces 590 on the ridges 59. Preferably, the ring 63 isformed of a thin band of 'high strength material, such asberyllium-copper alloy and is dimensioned so that the inner diameter ofthe ring is slightly less than the distance between the flattenedsurfaces on the ridges 59 on the diametrically opposite fingers.Accordingly, the ring 63 is under tension and is force fitted over thelower end of the body and moved upwardly thereon toward the blind end ofthe pin cavity 53.

The amount of inwardly biasing force exerted on the fingers 62 by thering 63 is selectively adjustable by movement of the ring 63 around thefingers of the receptacle 51. For example, the fingers 62 are moreeasily deflected near the outer or free ends, and when a ring of giveninternal diameter is positioned adjacent the free end, the fingers 62have less inward deflection of the free ends than when the ring 63 ismoved upward is bisected by a longitudinally extending slot 60 extend- Iing upwardly from the lower end of the connector and terminated adjacentthe inner end of the pin cavity 53.

The slots 60 bis ect the faces 58 into pairs of segments ofapproximately equal area, and thereby form a pluraltoward the blind endof the pin cavity 53. The flattened surfaces of the ridges 59 permiteasier movement of the ring 63 thereon without gouging of the ridges.

From the foregoing, it should be noted that the cable connector 50aprovides a large contact surface between the connecting members thereofand additionally provides for an adjustable contact pressure over thelarge contact surface. It is not necessary to tighten any bolts orclamps for assembling the cable connector once the connecting membersare engaged since ample holding force is achieved by the contactpressure between the connecting members. While the receptacle 51 isillustrated as having a square cross section, it is to be understoodthat other configurations, such as triangular, etc., could be used aswell. The fingers 62 are constructed to have a cross section that issymmetrical on opposite sides oflongitudinally bisecting planesextending between the ridges 59 and the longitudinal axis of the cableconnector 50. Accordingly, the inward force applied by the ring 63 tothe flattened ridge surfaces is distributed fairly uniformly on bothsides of the bisecting plane to the inner contact surface of the fingers62.

The upper end of the tubular housing 34 carries a conical skirt 65, FIG.2, so that a pair of spring latches 66 carried on the grounding cover 32can engage with the conical skirt 65 in any radial direction. The springlatches 66 include latch loops 67 designed to be engaged by standard hotline tools for latching or unlatching the various devices which carrythe standardized mating surfaces and latching elements. Suitable latchsprings 68 maintain the spring latches 66 in tight assembled relation.

The connector 50 also includes a switch connector 50b for interrupting acircuit under load. The switch connector 50b includes the samecomponents as the cable connector 50a but additionally hasarcextinguishingcomponents. Specifically, the switch con nector 50bincludes a switch receptacle 51a defining a switch cavity53a formed bythe fingers62. The tension ring 63'affords inward pressure to thefingers 62 in like manner as in the cable connector 500. The switchconnector 50b will accommodate a coupling conductor or switch member toprovide an excellent electrical connection. I

To provide for load-break features, the upper connector' opening carriesa liner 72 of arc-extinguishing material which co-functions with afollower 73 of arc extinguishing material within the switch cavity 53aof the switch receptacle 51a and which is backed up by a projectionspring 74 to provide load-break'effects when an associated couplingconductor is removed from the switch receptacle. The material of theliner 72 and follower 73 possesses desired arc-quench properties and maybe of synthetic polymer material carrying a suitable amount ofarc-quenching material such as molybdenum sulfide or alumina.

In operation the follower 73 moves into the opening in the liner 72 whena coupling conductor 77 of the grounding cover 32 is removed from theassociated switch cavity 53a. The cooperation of the. arcquenchingelements 72 and 73 extinguishes any arc that may be formed as thecoupling conductor 77 leaves the end. of the switch. connector 50 by deionization of the plasmafSince the arc is interrupted in the narrowspace between the follower 73 and the liner 72 and sincethe follower 73remains in the opening,

there 'is no significant amount of ionized gas between the separatedcircuit elements. That is, the ionized gases associated with-thereceptacle side of the circuit remain inside and those associated withthe connector side of the circuit are dissipated on the outside.

The connector 50 isin a receptacle chamber 80 in the relatively highpotential field associated with the cable conductor. This region wouldtherefore be subject to corona problems unless all the air spaces aroundthe receptacle are eliminated. This is accomplished according to thepresent invention by applying a conductive layer or member 81 to theinside wall of the chamber 80. .If desired, the conductive layer 81 maybe a conductive paint or coating.

The. inside wall of the receptacle chamber 80 includes two peripheralgrooves 82 and 83 of semicircular cross section, one 82 at the cableentrance end which serves to reduce the voltage gradient at the end ofthe conductive layer 81 because of the enlarged radius of curvatureprovided by the conductive surface of the groove, and one 83 generallycentrally of the receptacle chamber 80 which serves to lock theconnector 50 in proper position in the chamber by means ofa metallicspring ring 84. This ring 84 also serves to connect electrically theconductive layer 81 to the connector 50.

The outer surface of the hard dielectric filler 40.is also provided witha conductive layer or member, shown in the form of a conductive coating85 in the regions where it is normally in contact with themetal' housing34. This is to prevent ionization of air in the small gap between theinside surface of the housing 34 and the outside surface of the filler40 which may occur due to differences in the thermal expansioncoefficients of the two materials. This problem of differing thermalcoefficients ofexpansion also occurs between the soft dielectric filler38 and the metal-housings 34 and retainer 39.'I-Iowever, in theselocations the action'of the latch springs 68 and the thrust spring 37 onthe soft elastorner keeps all'of the critical in'terfacial surfaces invoid-free contact throughout the ranges of expected ambient temperaturesand operating conditions.

The grounding cover 32 serves to provide a positive ground to a cableterminal 30 when it is desired to work in the area of a disconnectedterminator. Tothis end, the coupling conductor 77 of the grounding coveris electrically connected to a metal grounding housing or cap 88 whichin turn is grounded to the spring latches 66 and the conical skirt 65 tothe grounded conducting housing 34 of the cable terminal. However-,anadditional ground connection is recommended to the grounding cap housingby means of a flexible ground wire connected to the terminal 88b. A softdielectric filler 90 fills the grounding cap around the couplingconductor 77 and forms avoid-free interfacial engagement with theconical sealing surface 41 of the cable terminal. As heretoforedescribed, the latch springs 68 serve to maintain a permanent void-freeinterfacial seal between the critical interfacial surfaces in a mannerThe structure shown in FIGS. 1, and 3 is particu- 'larly adaptedto'receive the co-axial cable which employs'the plurality of wires 48arranged in symmetrical spirals over the outside surface of the cable.These wires serve as the neutral conductor of the circuit as well as agrounded protective sheath. Since these wires 48 are part of the powercircuit, they must provide a high conductivity paththroughout thecircuit. For this reason, the lower cover 35 is provided with extensionmembers 92 which receive split. bolt connectors 93 for holding thestrands 48 of the neutral conductor so as to make connection and at thesame time hold the cable firmly in place. The neutral wires 46 can thencontinue on to be grounded to ground or other neutral wires ashereinafter described. The extension member 92 also serves as means forrotating the cover 35 into the closed and latched position. v

FIGS. 6, 7 and 8 illustrate a simple typical switch connection betweentwo cable terminals of the type heretofore described. As thereinillustrated, a pair .of cable terminals 30 identical to that heretoforedescribed, are supported in spaced relation from a grounding rod 95 byasuitable mounting clamp 96. The mounting clamp 96 is precisely machinedto match the diameter of the terminal housing 34 and includes a groove97 accommodating a rib 98, FIGS. 1 and 2, which is precisely located onall of the terminal housings 34. The mounting clamps 96 are slotted withgrooves 97 so as to fit the rib 98 whereby all of the terminals 30 arerigidly held in place at the proper leve with respect to the mountingclamp 96. Thus, all terminals 30 in a single mounting clamp will benormal to the plane of the bracket, at a standard distance apart andtrated in FIGS. 7 and 8, and provided with a loop 101 for engagementwith a lineman s hot stick. The switch coupler 100 includes a centralconducting assembly made up of two switch couplings or pins 104 servingas switch blades and braised or otherwise secured to a crossbar 105formed of electrically conducting materials such as copper. The switchcouplings are silverplated and carry a switch tip 104a which iscontrolled in size so as to fit the switch cavity 53a in the matingcable terminal. The horizontal portion of the central conducting membercarries a cylindrical molding of conductive plastic or other suitablematerial 106 to enlarge the radius of the conductive portions and reducethe potential gradient. This cylindrical molding of conductive material106 eliminates corona problems from airgapsin high gradient regionswhich could develop due to differences in thermal coefficients ofexpansion between plastics and metals. With this construction the fieldstarts at the outer surface of the conductive material 106 which issurrounded in bonded, void-free relationship with a hard dielectricfiller 107 of the same expansion coefficientas the conductive material106 so as to remain sealed at all temperatures. The entire assembly isenclosed within a conductive housing here illustrated as a stainlesssteel housing 108, formed of mating housing portions 108a and 108b, sothat the filler assembly including the contact plugs 104, crossbar 105,conductive material 106, and hard dielectric filler 107 may beprefabricated and then assembled in order to establish the void-freeinterface under the spring forces of the standard latch system. This isaccomplished by providing conical cavities 110 around the switchcoupling 104 in the dielectric filler 107 which are larger than thestandardized conical sealing surface 41. A soft dielectric molding 111is preformed with the exact geometry of the space between the conicalcavities 110 and the conical sealing surfaces 41 to provide the standardconical sealing surface 91. The soft dielectric fillers 110 are formedof double cones bonded to the hard dielectric filler 107 on the coupler100 to provide a permanent void-free'interface between the hard and softdielectrics in the coupler 100. Each of the downwardly dependingportions of the coupler housing are provided with a pair of latchsprings 66 at the ends oflatch loops 67 and adapted to be loaded throughlatch springs 68 in the manner described in embodiment of FIGS. 1, 2 and3.

By the proper selection and arrangement of grounded surface elements, avariety of important distribution system functions can be performedaccording to the present invention. FIGS. 9, 10 and 11 illustrate, forexample, an assembly 120 of standard elements arranged so as to providea single fuse tap, illustrated in phantom at 114, on an undergrounddistribution loop circuit. Sectionalizing functions are provided bymeans of two switch couplers of the type illustrated in FIGS. 6 to 8.The necessary interconnections are established by means of a threeterminal manifold or bus and three cable terminals 30. Each cableterminal 30 is identical with that of FIGS. 1, 2 and 3. In addition, themanifold 115, as illustrated, is provided with three vertical risers orcable terminals 116 each containing similar load-break features. Thus,each riser 116 is an exact replica in form and function as the upper endof the standard cable terminal. Each riser housing includes a locatingrib 117, FIG. 11, and latching cone 118 so that all removable componentswill interfit. Thus, one of the risers 116 and one of the cableterminals 30 are tied together by the mounting clamp 96 onto thegrounding clamp 95. The remaining two vertical risers 116 and cableterminals 30 are connected by a 4-place mounting clamp 122 secured to agrounding rod 123. Each of the clamping portions of the mounting clamp122 is provided with a circumferential groove 124, FIG. 10, receivingone of the locating ribs 98 and 117 to vertically position therespective terminals.

The design details of the multi-terminal manifold 115 will be moreclearly understood by reference to FIG. 11. As therein illustrated, themanifold 115 includes a central conductor 128 which may be of copper orother suitable material. Standard switch connectors 50b, identical withthe switch connectors 50b of the connector 50 illustrated in theembodiment of FIGS. 1, 2 and 3, are braised to the central conductor128. Briefly,

therefore, the switch connectors 50b each include the switch receptacle51a provided with the switch cavity 53a for receiving a mating connectorrod. As heretofore described, the switch receptacle 51a is similar tothe switch receptacle 51a illustrated in FIGS. 4 and 5 and include theplurality of fingers 62 encircled by the tension ring 63. The liner 72of arc-quenching material leads into the switch cavity 53a, and theprojectable follower 73 is biased into the liner 72 by the projectionspring 74 when connecting components are not in place. It is understoodthat the load-break components including the sleeve 72, follower 73, andprojecting spring 74 may be omitted where it is not desired to providefor breaking of the circuit under load.

In like manner as with the switch coupler 100 illustrated in FIGS. 7 and8, a conductive material 130 is cast around the middle connectingcircuit components thereby enlarging the radius of the conductingportion.

and reducing the potential gradient. Thus, there is eliminated thecorona problems from air gaps in high gradient regions which coulddevelop due to differences in thermal coefficients of expansion betweenthe metal parts and the dielectric fillers. With this construction, thefield starts at the outer surface of the conductive material 130.However, since the upper ends of the switch receptacle 51a in the regionof the follower 73 must be movable, a soft cover 131 of plastic or othersuitable material covers the free end of the switch receptacle 51a. Ahard dielectric filler 132 is molded over the entire conducting systemwith the outside surfaces conforming to a housing 133 of stainless steelor other suitable material and with the standard conical sealing surface41 of each riser position. The entire manifold assembly 115 may bepreformed and inserted into an upper housing portion 133a with a lowerhousing portion 133b slipped into position and with end caps 134 spotwelded into place. As in previous components, the outside surface of thehard dielectric filler 132 is covered with a conductive layer 135 excepton the conical sealing surfaces.

The risers 116 may be provided in any number; however, most circuitrequirements can be met with three or four terminal manifolds. It shouldbe noted that the risers are arranged in line and spaced the standarddistance apart. Also, the vertical sleeve portions of the housing 133are fully standardized to fit brackets and to mate with removablecomponents. Thus, two four terminal manifolds can be combined to providesectionalized switches and four fused taps in a single control center.

Surge production is' frequently desired at the open A end of a loopcircuit or other suitable locations when it is to remain inthiscondition for a long period of time. FIG. 12 illustrates in partialcross section a surge arrestor 140 which may be connected. to any of thestandard terminals in a cluster or control center. The surge arrestor140 includes a groundi ng housing 141 of stainless steel or othersuitable material and includes a lower portion l4la which isstandardized with the coni-' cal sealing surface 41 to the fit cableterminals and multiterminal'ma'nifolds of the grounded surfacedistribution system. According to the present invention, the functionalparts of the surge arrestor 140 include a system of quench'gaps 142 inseries-with valve blocks 143 of suitable material such as siliconcarbide-These elements are arranged in a dielectric tube 144 undercompression of a compression spring 145. The housing includes a topcover 146 locked to the remainder of the housing through side pins inlike manner as cover in the embodiment of FIGS. 1, 2 and 3. Thespacebetween: the dielectrictube 144 and the metal housing 141 isfilled;witha soft dielectric filler 147 which is maintained in void-freeinterfacial contact by means of the inner thrustspring 37 acting betweenthe end cover 146 and the retainer 39. A connector pin 148 extends fromthe lowerendof thesurge arrestor 140 for mating 'withinthe switch cavity53a ofa collaborating member.

A cone of soft dielectric material 149 is placed around the upper end ofthe contact plug 148 in order to control the gradient in thisregion. Itis understood that the connecting components of the lower housing 141aare identical to those heretofore described, including the springlatches 66, the latch loops 67, and the latch springs 68 which serve thedual function of biasing the spring latches 66 and applying a positivepressure to thedielectric filler-147.

- To provide for fusing of the grounded surface distribution system, oneof the interchangeable elements may consist of a current limiting fuse,such as the current limiting fuse 152, illustrated in FIG. 14. Astherein illustrated, the current limiting fuse 152 is housed within anassembly similar to the switch coupler 100 more fully described in thediscussion of FIGS. 7 and 8. More specifically, there is provided thefuse unit 153 enclosed within a metal housing 154, similar to housing108 heretofore described, and cast inthe center of a hard dielectricfiller '155. A pair of conically shaped soft dielectric fillers 156 areprovided having the standard conical sealing surfaces 91 for engagingthe conical sealing surface 41 of cable terminals or manifolds, and thefuse 152 is provided with the standardized latches to interfit with theother components.

Referring now to the fuse unit 153, the operation thereof is known anddepends upon the melting and vaporization of a silver fuse wire 157 andthe subsequent deposition of the silver over the surfaces of sand grains158 which surround it. This takes place so rapidly under high faultconditions that the current is cut off before it reaches the full valueof the available fault current. The silver metal becomes so diffused inthe sand grain matrix that it no longer carries significant current. Insuch fuses it is necessary to maintain sufficient distance between theturns of the silver wire to prevent hot ionized gas from shorting outturns. In the illustrated design, in order to minimize the length of thefuse for a given rating, a wide flange surrounding the spiral core 159is used to separate the turns of the silver fuse wire 157. As previouslymentioned, this space around the wire between the spiral flanges isfilled with refractory granules such as alumina or silica. The granularmatrix may be bonded with a minimum of refracto ry cement in order topermit the assembly of the parts within an insulating tube 160. The tube160 may be of organic .or inorganic material, but preferably it is ofhigh strength and refractory at least in its liningin order. to minimizeinternal pressures which may develop duringoperation. This fuse has nooutlet'for gaseous discharge since its entire envelope must be capableof withstanding system I voltages within the grounded housing. Therespective ends of the silver fuse wire 157 is soldered to the center ofopposed cylindrical ferrules 161 fitted over the ends of the surroundingspirals 159 and insulating tube 160. Thus, the silver fuse wire 157 maybe of maximum length. A pair of contact rods' or plugs 162 extendconcentrically through the soft dielectric filler for engagement withina plug receiving have some. salvage. value for factory rebuilding, butcannot be rebuiltin the field. FIGS. 15 and 16 illustrate.

a current limiting fuse 165 which, although somewhat more expensiveinitially than the fuse 152, may have the active element replaced by theuser in the field, and the fuse unit 165 could go back into serviceimmediately. a I

The principle of operation of the fuse 165 is similar to that of fuse152 and includes the silver fuse wire 157- between-the flanges of thespiral core 159-filled with suitable refractory granulars or sand grains158. This activefuse element is housed within removable fuse cartridge166 which can be removed from a metal housing 167 for replacement byreleasing one or both of a pair of opposed end thrust spring covers 168and unscrewing a pair of contact rods or plugs 169 from plug blocks 170.In the fuse 165, the entire space between the housing 167 and the fusetube 166 is filled with soft dielectric filler 171 and is maintained invoidfree contact by end thrust springs 172 interposed vbetween thespring covers 168- and respective retainer cups 173. A bayonnetconnection joins the spring covers 168 with the housing 167 ina mannersimilar to that

1. An accessory for high voltage electric power conductor terminationsof the type having first and second conductor terminations withrespective end surfaces comprising a module releasably positionedbetween the respective end surfaces of said first and secondterminations, insulated electrically conductive means in said module,means for electrically connecting the respective conductor terminals insaid termination to said conductive means whereby a current carryingcircuit is completed between said terminals through said module, meansfor forming water-tight uniform voltage grading seals between the endsof said module and the respective terminations when said currentcarrying circuit is completed, and current interrupting means mountedwithin said module for interrupting the current carrying circuit betweensaid terminals.
 2. An accessory as defined in claim 1 including anelectrical outlet terminal disposed on said module and electricallyconnected to said conductive means.
 3. An accessory as defined in claim1 including a plurality of electrical outlet terminals disposed on saidmodule, each of said terminals being electrically connected to saidconductive means.
 4. An accessory as defined in claim 1 wherein saidcurrent interrupting means comprises a current limiting fuse.
 5. Anaccessory as defined in claim 1 wherein said current interrupting meanscomprises a cartridge-type fuse that is removably mounted in saidmodule.
 6. An accessory for high voltage electric power conductorterminations of the type having first and second conductor terminationswith respective end surfaces that form a water-tight, voltage gradingseal therebetween when moved into operating position to detachablyconnect their respective conductors in electrically conducting relationcomprising, a module adapted to be releasably positioned between therespective end surfaces of said first and second terminations, saidmodule having first and second end surfaces that are generallyfrusto-conical and respectively substantially complement the endsurfaces of said first and second terminations to form a water-tightuniforming voltage graded seal therewith, insulated electricallyconductive means in said module forming a conductive circuit between thefirst and second end surfaces of said module, a cartridge-type fusemounted in said module and positioned in series with said circuit forinterrupting said circuit when a predetermined over-current passestherethrough, and means for electrically connecting the respectiveconductor terminals in said terminations to said conductive meansadjacent opposite ends of said fuse whereby an electric circuit iscompleTed between said terminals through said fuse.
 7. A three-part fusemodule for high voltage electric power conductors comprising first andsecond conductor termination modules and a fuse supporting module, saidfirst and second modules having respectively generally frusto-conicalend surfaces that form water-tight, voltage grading seals with oppositeends of the fuse supporting module when coupled in operating positiontherewith, a liner of inslulating material within said fuse supportingmodule formed to accommodate a cartridge-type fuse and maintain itsterminals in electrical contact with the terminals of said terminationsand means for electrically connecting the respective conductor terminalsin said terminations to opposite ends of a cartridge-type fusepositioned in said liner whereby an electric circuit is completedbetween said terminals by a fuse mounted in said liner.
 8. An accessoryfor high voltage electric power conductor terminations of the typehaving first and second conductor terminations with respective endsurfaces that form a water-tight, voltage grading seals, comprising amodule releasably positioned between the respective end surfaces of saidfirst and second terminals, insulated electrically conductive means insaid module, means for electrically connecting the respective conductorterminals in said termination to said conductive means whereby a currentcarrying circuit is completed between said terminals through saidmodule, means for forming water-tight uniform voltage grading sealsbetween the ends of said module and the respective terminations whensaid current carrying circuit is completed, and current interruptingmeans mounted within said module for interrupting the current carryingcircuit between said terminals.
 9. An accessory as defined in claim 8wherein said current interrupting means comprises a current limitingfuse.
 10. An accessory as defined in claim 8 wherein said currentinterrupting means comprises a cartridge-type fuse that is removablymounted in said module.
 11. An accessory for high voltage electric powerconductor terminations of the type having first and second conductorterminations with respective end surfaces that form a water-tight,voltage grading seals, a module adapted to be releasably positionedbetween the respective end surfaces of said first and secondterminations, said module having first and second end surfaces that aregenerally frusto-conical and respectively substantially complement theend surfaces of said first and second terminations to form a water-tightuniforming voltage graded seal therewith, insulated electricallyconductive means in said module forming a conductive circuit between thefirst and second end surfaces of said module, a cartridge-type fusemounted in said module and positioned in series with said circuit forinterrupting said circuit when a predetermined over-current passestherethrough, and means for electrically connecting the respectiveconductor terminals in said terminations to said conductive meansadjacent opposite ends of said fuse whereby an electric circuit iscompleted between said terminals through said fuse.
 12. A three-partfuse module for high voltage electric power conductors comprising firstand second conductor termination modules and a fuse supporting module,said first and second modules having respectively generallyfrusto-conical end surfaces that form watertight, voltage grading sealswith opposite ends of the fuse supporting module when coupled inoperating position therewith, a liner of insulating material within saidfuse supporting module formed to accommodate fuse means and maintain itsterminals in electrical contact with the terminals of said terminations,means for electrically connecting the respective conductor terminals insaid terminations to opposite ends of said fuse means positioned in saidliner whereby an electric circuit is completed between said terminals bysaid fuse means mounted in said liner, and a layer of high resistancecOnductive material on the exterior surface of said liner.
 13. A fusefor high voltage electric power conductors comprising a fuse supportingmodule, fuse means within said fuse supporting module, a liner ofinsulating material within said fuse supporting module accommodatingsaid fuse means, means for electrically connecting the respectiveterminals of said fuse means to electric circuit terminals whereby anelectric circuit is completed between said terminals by said fuse meansmounted in said liner, and conductive means within said module betweenand immediately adjacent to both said fuse means and said liner,electrically connected between said respective terminals of said fusemeans for preventing the formation of corona within the area between thefuse means and the liner.
 14. A fuse device in a high voltage powerdistribution system for electrically interconnecting a first componentof said system with a second component of said system, said fuse devicecomprising an elongated, current-limiting fuse module, means forsupporting and insulating said fuse module, said supporting andinsulating means comprising an elongated insulating housing, a firstterminating portion, said first terminating portion including agenerally frusto-conically shaped surface for engaging a complimentarilyshaped surface of said first component, a second terminating portion,said second terminating portion including means for securely physicallyand electrically engaging said second component, electrically conductivemeans disposed on the outer surface of said insulating housing formaintaining said outer surface at a reference potential and meansengageable by an elongated insulating tool for enabling said fuse deviceto be remotely manually moved into and out of engagement with said firstcomponent.
 15. A fuse device as defined in claim 14 wherein saidsupporting and insulating means comprises means for removably mountingsaid fuse module in said fuse device and wherein said fuse modulecomprises a removable and replaceable current-limiting fuse module. 16.A fuse device as defined in claim 15 wherein said removably mountingmeans comprises means for retaining said fuse module within saidinsulating housing and for enabling said fuse module to be removed fromone end of said insulating housing.
 17. A fuse device as defined inclaim 14 wherein said first terminating portion further includes afirst, rigid, conductive, depending portion for engagingcurrent-carrying coupling means of said first component.
 18. Incombination, a first terminal of a first component of a high voltagepower distribution system, said first terminal including a firstinsulating housing, a first conductive grounding shield surrounding saidfirst housing and a first current-carrying coupling means disposed insaid first housing, a second terminal of a second component of saidsystem, said second terminal including a second insulating housing, asecond conductive grounding shield and a second current-carryingcoupling means disposed in said second housing, said first housing andsaid first shield being physically distinct from said second housing andsaid second shield, respectively, means for securely engaging said firstand second shields to maintain said first and said second terminals in arigid, fixed, stationary, spaced-apart relation, and a fused coupler forelectrically connecting said first component to said second component,said fused coupler comprising a first conductive portion for engagingsaid first coupling means, a second conductive portion for engaging saidsecond coupling means, a current-limiting fuse electricallyinterconnecting said first and second portions and forming a generallyU-shaped coupling assembly with said first and second portions, saidfuse including an outer insulating tube, a solid insulating housingsupporting and enclosing said fuse, solid insulating means encircling atlEast a major portion of said first portion and at least a major portionof said second portion, first conductive means disposed on the outersurface of said solid insulating housing and on the outer surface ofsaid solid insulating means electrically insulated from said first andsecond conductive portions and from said fuse for maintaining said outersurfaces at a reference potential, means for releasably securelyengaging said fused coupler with said first and second terminals suchthat said first and second conductive portions are maintained in aphysical and electrical engagement with said first and second couplingmeans, respectively, upon the secure engagement of said coupler withsaid first and second terminals by said engaging means, and meansengageable by an insulated elongated tool for enabling said coupler tobe remotely manually moved into and out of engagement with said rigid,fixed, stationary, spaced-apart first and second terminals.
 19. Acombination as defined in claim 18 wherein said solid insulating housingcomprises means for removably mounting said current-limiting fuse insaid fused coupler and wherein said current-limiting fuse comprises aremovable and replaceable current-limiting fuse module.
 20. Acombination as defined in claim 19 wherein said removably mounting meanscomprises means for retaining said fuse module within said solidinsulating housing and for enabling said fuse module to be removed fromone end of said solid insulating housing.
 21. A combination as definedin claim 18 further comprising second conductive means for providing asubstantially large electrical resistance from one end of said fuse tothe other end of said fuse, said electrical resistance providing meansbeing disposed on the outer surface of said insulating tube.
 22. A fusedevice for electrically interconnecting a first terminal of a firstcomponent of a high voltage power distribution system with a secondcomponent of said system, said first terminal having a centrallydisposed current-carrying coupling means, said fuse device comprising afirst rigid, conductive, depending portion for engaging said couplingmeans of said first terminal, a second conductive portion forelectrically engaging said second component, a fuse module electricallyinterconnecting said first and second portions, said fuse modulecomprising a current-limiting fuse and an insulating housing surroundingsaid current-limiting fuse, solid insulating means having an innersurface and an outer surface enclosing said fuse module, said solidinsulating means comprising means for removably mounting said fusemodule in said fuse device, said removably mounting means includingmeans for enabling said fuse module to be removed from one end of saidsolid insulating means and to be replaced by another fuse module, firstconductive means on said outer surface of said solid insulating meansfor maintaining said outer surface of said solid insulating means at areference potential, and means engageable by an insulated elongated toolfor enabling said fuse device to be remotely manually moved into and outof engagement with said first terminal.
 23. A fuse device as defined inclaim 21 further comprising second conductive means for providing asubstantially large electrical resistance from one end of said fusemodule to the other end of said fuse module, said electrical resistanceproviding means being disposed on the outer surface of said insulatinghousing.
 24. A fuse device for electrically connecting both a firstterminating end of a first component of a high voltage powerdistribution system and a second terminating end of a second componentof said system with a third component of said system comprising a firstconductive portion for engaging a current-carrying coupling means ofsaid first terminating end, said first conductive portion comprising afirst electrical connector of one mating configuration, a secondconductive portion for Engaging a current-carrying coupling means ofsaid second terminating end, said second conductive portion comprising asecond electrical connector of said one mating configuration, a fusemodule electrically interconnecting said first and second portions andforming a rigid coupling assembly with said first and second portions,said fuse module comprising a current-limiting fuse and an insulatinghousing surrounding said current-limiting fuse, a first solid insulatingmeans enclosing said fuse module, first conductive means on the outersurface of said first solid insulating means for maintaining said outersurface at a reference potential, and means permanently electricallyconnected with said coupling assembly for forming a terminal or tap forelectrically connecting said first and second components with said thirdcomponent, said terminal or tap forming means comprising enclosure meanshaving a generally conically-shaped surface for engagement with acomplimentarily-shaped surface of said third component, said enclosuremeans surrounding a fourth conductive portion for engaging acurrent-carrying coupling means of said third component, said fourthconductive portion comprising a third electrical connector of theopposite mating configuration than said one mating configuration.
 25. Afuse device as defined in claim 24 further comprising second conductivemeans for providing a substantially large electrical resistance from oneend of said fuse module to the other end of said fuse module, saidelectrical resistance providing means being disposed on the outersurface of said insulating housing.